Various metering devices have been developed which print unit value such as postage meters, tax stamp meter, carrier payment systems and the like. A postage meter prints an indicia which is representative of money, thus, postage meters may be considered machines for printing money (i.e. symbols having value). Therefore, security has always been considered an important aspect of the postage meter operation. In prior postage meters an indicia is printed by a letter press, using a uniquely engraved die containing posta information such that the resulting imprint would be traceable to the particular meter. Newer postage meters have been developed that include electronically controlled printers such as thermal printers, ink jet or dot matrix pin printers for printing the indicia. One way to secure the validity of particular indicia has been to encode a message in the indicia such a manner that an unauthorized person who does not know the encryption scheme cannot reproduce the appropriate encoding.
Yet more recent postage verification methods utilize barcode technology taught in U.S. Pat. No. 4,660,221 to Dlugos for System for Printing Encrypted Messages With Bar-Code Representation and assigned to the assignee of the present invention. Furthermore, U.S. Pat. No. 4,949,381 to Pastor for Electronic Indicia in Bit-Mapped Form and assigned to the assignee of the present invention discloses the use of "public key" encryption systems. These systems provide two keys one of which is used to encrypt, but not to decrypt a message and a second key which is used to decrypt the message. These systems, however, have not provided a simple means for postal employees to visually detect the validity of the mail piece.
Various postage-metering systems also have been created in which other a print graphic may be included. The print graphic may be included for aesthetic, advertisement, or information value. The print graphic may be a meter ad, inscription user graphic and/or messaging. the print graphic may also be either customized or standardized. This print material also provides a level of personalization and customization for the user. Inclusion of print graphic is presently available in postal system developed by Pitney Bowes Inc. The print graphic is normally included near the indicia but may appear anywhere on the document. In most open system implementations, a computer generates mail piece information and sends it to a printer. In typical systems, mail piece information may include a destination address, a return address, a proof of postage payment (indicia), and print graphic. The print graphic may also be included in a return address.
U.S. Pat. No. 5,168,804 to Lee et al. for a Postage Meter Having an Automatic Slogan Sub-Module, discloses a postage meter having an automatic slogan sub-module wherein the postage meter has the ability to print an ad slogan or postage class indicia automatically, through the use of print cubes having print faces. The print faces could be independently or selectively rotated to position a respective print face within said print meter slogan aperture. The print face itself, however, can not be altered nor does the slogan provide a means for validating the print means.
Advertising slogans have also been made available to customers as a print die, which has been inserted in a print drum or perhaps as a rotatable slug as shown in U.S. Pat. No. 4,519,311 to Lowe for Auxiliary Printing Device For A Postage Meter. U.S. Pat. No. 4,831,554 to Storace et al. for a Postage Meter Message Printing System assigned to the assignee of the instant application shows a postage meter system for printing slogans and for changing such slogans by way of downloading by telephone from a database at a date center. U.S. Pat. No. 5,509,109 to Kim et al. for a Slogan and Inscription Control System For Mailing Machine, discloses a digital inscription and slogan printing system in which a slogan or inscription is easily changed and yet, which will allow sufficient monitoring to preclude illegal slogans from being printed. However, the ad slogan does not provide a means for validating the mailpiece.
In addition to providing a variety of advertising and messaging slogans, postage metering devices, both closed and, of course, open systems, have included the ability to print variable information through the use of thermal printers, ink jet printers and other printers. This prior art has provided a means for printing ad slogans or other messaging information on the envelope and separately, indicia for validating the postal payment. However, the print message itself has not provided a means for authenticating indicia information.
Generally, each post office is required to inspect the validity of a mail piece at least twice a year. Therefore, significant time may pass between inspections during which fraudulent mail may travel undetected through the postal system. An interest has developed in providing a postal authority with visual detection of fraudulent mail pieces, therefore, enhancing mail piece security.